Minimally invasive surgical treatment of spondylolysis in sportsmen and sportswomen
Nick Birch and David Harrison look at treatment and management of spondylolysis in adolescents and following skeletal maturity
Spondylolysis – a stress fracture of the pars interarticularis – is a common cause of low back pain in children and adolescents, particularly those who are engaged in athletic pursuits [1]. In the Caucasian population, 4.4 per cent of children have pars fractures by the age of six, rising to 6 per cent by the age of eighteen. The condition is more common in boys than girls and the fractures all occur before skeletal maturity [2]. It is recognised as being significantly more common in athletes [3].
There is a clear genetic variation across the world with people of African descent having a very low prevalence but almost half of people of Inuit descent will have spondylolysis.
The great majority of fractures occur at L5 (87 per cent) with 10 per cent occurring at L4 and 3 per cent at L3. In 4 per cent of cases there are multiple levels of involvement and in 80 per cent of the fractures are bilateral [4].
After skeletal maturity, it is rare for spondylolysis to develop except in certain groups of athletes such as cricketers, tennis players, rugby players, weight lifters and track and field competitors.
Clinical presentation
The presentation of spondylolysis in sporting teenagers commonly is low back pain that arises after a period of intense athletic activity when the individual is trying to excel in their sport. For girls this is commonly gymnastics and for boys cricket, rugby and football. It is not uncommon for teenagers to experience low backache or pain but in general, it is self-limiting. When it becomes persistent, the diagnosis of spondylolysis should be considered. In the growing spine, if the stress fractures are bilateral under certain biomechanical conditions, forward slippage of the upper vertebra on the lower can occur leading to spondylolisthesis.
The typical pattern of presentation in the teenager at risk is dull, symmetrical low back pain without radiation to the lower limbs (although buttock pain is common) that is worst during and after exercise particularly involving hyperextension. Rest usually eases it. Examination findings can vary from normality to slight lumbar stiffness and discomfort when extending the low back, although in the acute phase when the pain is severe marked muscle spasm and hamstring tightness is often present. When there is no spondylolisthesis neurological examination is usually normal [5].
Imaging
If a teenager presents with persistent low back pain and is considered to be at risk an MRI scan is the first line investigation as it does not involve ionising radiation. The MRI can show the earliest signs of stress within the pars interarticularis and the adjacent pedicle very well. Once a fracture has occurred the MRI might still demonstrate oedema adjacent to the defect indicating that the injury is recent. However, the investigation of choice to understand whether the fracture is healing or not, is a limited CT scan with coronal and sagittal reconstructions. This will show whether the fracture is fresh (acute), established but perhaps healing (progressive) or a non-union (terminal lesion). Standing lumbar spine X-rays (AP, lateral and 45° oblique) are able to show a pars fracture as the classical radiological sign of the ‘collar on the Scottie dog’ and if a slip is suspected the grade can